/Engine/Source/Runtime/Engine/Public/HLSLTree/HLSLTreeCommon.h
Creates a new expression representing this expression on the previous frame.Bydefault returns nullptr, which means the previous frame is the same as the current frame
virtual const [FExpression](API\Runtime\Engine\HLSLTree\FExpression) * ComputePreviousFrame ( [FTree](API\Runtime\Engine\HLSLTree\FTree) & Tree, const [FRequestedType](API\Runtime\Engine\HLSLTree\FRequestedType) & RequestedType ) const